Observation of Wind‐Produced Doppler Shifts in Tropospheric Scatter Propagation

Abstract

Persistent average frequency shifts obtained from phase data have been consistently observed on a 230-km closed-loop troposcatter circuit when the antennas were synchronously pointed off the great-circle azimuth. The magnitude of the "Doppler shift" systematically increases with the antenna pointing angle from the great circle. The sign of the Doppler shift reverses across the great circle and depends upon the direction of the crosspath wind simultaneously observed in the lower common volume. Average Doppler shift data are presented for several fixed-antenna-offset and antenna-beamswinging experiments conducted under varied meteorological conditions. Observations are interpreted in terms of atmospheric "scatterers" drifting across the path at the average crosspath wind speed. A model based on phase geometry is derived for the average Doppler shift and for Doppler spectra in terms of the crosspath wind velocity, antenna patterns and propagation mechanism.It is concluded that Doppler frequencies observed with a bistatic transhorizon microwave system depend primarily upon crosspath wind speed and the prevailing atmospheric structure. Crosspath motions thus appear to be an effective source of interference fading in tropospheric transhorizon propagation.

Electromagnetic Wave Reflection from Shocked Dielectric Materials

“…Due to the Doppler effect generated at each moving interface, the radial frequency ( ) in Eq. (1) differs from the radial frequency of the incident electromagnetic field and according to [2], it can be approximated by the following relationship:…”

Review of Techniques in Transhorizon Propagation Research and their Relationship to Parameters of the Troposphere

“…Birkemeier [1968] has interpreted some of the Rake data of Abraham and Barrow discussed in the preceding paragraph. (Since this review was written, further interpretation of the Rake data has been reported by Birkemeier et al [1968Birkemeier et al [ , 1969.) Birkemeier's interpretation is based on atmospheric scattering models and weather bureau data taken during the experiments.…”

Electromagnetic wave propagation in inhomogeneous, moving media: A general solution of the problem

“…Measurements in communication investigations, in space research and in radio astronomical experiments [e.g., Adam , 1948; Birkemeier et al , 1968; Bird , 1976; Goldstein , 1969; Higgs , 1960; Jacobs and Watanabe , 1966; Sadeh et al , 1968; Woo et al , 1976] demonstrated the importance of a complete full‐wave solution, and in this moment it is impossible to exclude that the effects caused by the signal propagation through the interplanetary, moving, inhomogeneous media in the outer solar system from the spacecrafts to the Earth has an important role in the “Pioneer anomaly” [see, e.g., Anderson et al , 1998]. To clarify the possible role of different factors in these measurements it is necessary to derive a correct, complete full‐wave solution of Maxwell's equations in this important (special relativistic) case.…”

“…The investigation of the frequency shift and line broadening with limited accuracy was applied earlier in a ray‐tracing approximation for the quasi‐monochromatic signals, the “relativistic ray tracing” [ Ferencz , 1980a], some results on the interpretation of measured data are given by Ferencz [1980b]. Some results of the application of the classic scattering theory on the interpretation of data measured in terrestrial communication experiments are given by Birkemeier et al [1968]. A method was developed for the investigation of the rotation of the signal polarization [ Ferencz , 1978a, 1978b] but without the derivation of a complete full‐wave solution.…”